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Smith and Terrile are now busy photographing three other stars known to have surrounding matter, including one thought to be almost as old as the sun. By the end of the year, the IRAS team will release the names of 40 more stars that they believe may be girdled by solid material. Says Jet Propulsion Laboratory's chief space scientist, Moustafa Chahine: "If you can imagine what Galileo was thinking when he first looked at Jupiter, and where we are now, it can give you an idea of where we'll be in the very near future. We have to start thinking about making an interstellar visit."
As if their spectacular Beta slide show was not enough, Terrile and Smith presented another dazzling photograph last week from the Las Campanas Observatory. This one was of objects closer to home: the first clear image of the rings around Uranus, the third largest planet in the solar system and the seventh farthest from the sun. The rings were first discovered in 1977, when Uranus passed in front of a very bright star and repeatedly dimmed that distant sun's light. Scientists soon decided that the peculiar smudging was caused by the planet's nine rings, the largest of which is 63,600 miles in diameter.
Unlike the glittering braids around Saturn, which are composed of strands of ice fragments, the Uranus rings are dark, reflecting only 2% of the sunlight that strikes them. Astronomers theorize that these somber necklaces are made either of a kind of carbon material, scavenged from the outer edges of the solar system and much less reflective than charcoal, or of frozen methane gas that has been blackened after long exposure to a radiation source. Says Terrile: "There might be a trapped radiation field around Uranus, just as there is around earth and Jupiter." Final answers may have to wait until 1986, when the Voyager 2 spacecraft, launched in 1977, will swing past Uranus to get a better view.
—By Natalie Angier.
Reported by Meg Grant/Los Angeles